module ArrayExtras
  def a_oracion(options = {})
    to_sentence(options.reverse_merge(:connector => 'y', :skip_last_comma => true))
  end
end
module HashExtras
  def asumir(*args)
    args = {args[0] => args[0]} if args.size == 2
    args.each{|k, v| self[k] = v if self[k].nil? }
  end
end

Array.send :include, ArrayExtras
Hash.send :include,  HashExtras
